Special counsel Robert Mueller's investigation is now focusing on an alleged meeting between short-lived national security adviser Mike Flynn and Rep. Dana Rohrabacher (R-Calif.) ahead of the 2016 presidential election.

The meeting, which allegedly took place in September 2016, was arranged by Flynn's lobbying firm and was attended by Flynn; Rohrabacher; Flynn’s business partners, Bijan Kian and Brian McCauley; and Flynn’s son, Michael G. Flynn, according to NBC News.

Rohrabacher is notoriously pro-Russia. In the past, the California congressman has been an advocate for improved U.S.-Russia relations. In addition, he spoke in favor of repealing the Magnitsky Act, a bill intended to punish Russian officials responsible for the death of Russian tax accountant Sergei Magnitsky in a Moscow prison in 2009.

While investigators are only questioning witnesses about the potential meeting and not the direct players of interest, this is the first known time Mueller's investigation has turned its focus to a member of Congress.

Flynn came under a good deal of scrutiny during his time in the Trump administration over his lobbying work for the Turkish government, which he did not disclose prior to being instated as a national security adviser.

Additionally, Flynn resigned after it was revealed that he lied to Vice President Mike Pence about the nature and content of his communications with the Russian ambassador to the United States, Sergey Kislyak.

According to NBC, Mueller has enough information on both Flynn and his son to proceed with an indictment.